Thermoelectric switch



Oct. 4, 1932. R. DE FRANCESCHI 1,880,367

THERMOELECTRIC SWITCH Filed Dec. 23, 1929 I N VEN TOR.

Jiena DeFmncesck i ATTORNEY.

Registered Oct. 4, 1932 PATENT FFFECE RENO DE FRANCESCHI, OF WASHINGTON, DISTRICT OF COLUMBIA THERMOELECTRIC SWITCH Application filed December 23, 1929. Serial No: 416,163.

This invention relates to a thermo-electric switch particularly adapted for use in con nection with fire alarm systems but it is to be understood that a system in accordance with this invention may be employed for any purpose for which the same is found to be applicable.

The primary object of the invention is to provide, in a manner as hereinafter set forth, a thermoelectric switch in a normally open circuit which isadapted to close the circuit upon being subjected to heat, whereby the circuit may operate a firealarm, sprinker system, or the like.

A further object of the invention is to provide a thermoelectric switch of the character aforesaid, in which the switch points are housed within a combined protector and support element provided with means to permitthe ready access of heat thereinto, whereby the switch is protected from deterioration of the parts during long periods of inactive use, and therefore is maintained in proper condition to successfully operate in the manner intended when suddenly brought into active use. a

A further object of the invention is to provide a thermoelectric switch of the character aforesaid which includes a pair of conductors normally separated by a readily fusible substance, and in which one of the conductors is provided with means to insure positive engagement thereof with the other conductor upon the melting of the fusible substance.

With the foregoing and other objects in view, the invention consists of the novel construction, combination and arrangement of parts as hereinafter more particularly de scribed, and as illustrated in the accompanying drawing wherein is shown an embodiment of the invention, but it is to be understood that the description and drawing are to be taken as illustrative and that the invention is intended to be limited only by the scope of the claims hereunto appended.

In the accompanying drawing in which like numerals are employed to designate like parts throughout the same Figure 1 is a sectional View of a switch in accordance with this invention, showing the same in association with a fire alarm system, shown diagrammatically.

Figure 2 is an enlarged plan of the switch showing the cover for the combined support and protector element in open position.

Figure 3 is a longitudinal section showing the combined support and protector element in position on a ceiling.

Figure 4 is a sectional elevation showing the relative position of the contacts for the conductors after the fusible substance has been melted.

Figure 5 is a perspective view of the combined support and protector element.

Referring to the drawing in detail, there is shown diagrammatically in Figure 1 a fire alarm system to illustrate one of the uses to which the invention may be put. The fire alarm system as shown includes an audible signal 1 and a source of electrical energy 2 which are connected in series by means of a pair of conductors 3 and 4 to provide a circuit therebetween, such circuit normally being maintained open by my improved switch 5 and operating when closed to actuate the signal 1.

The switch 5 includes a combined support and protector element 6 of box-like form and provided with a hinged cover 7 formed with slots 8 to permit the ready entrance of heat into the interior of the element 6 when the cover 7 therefor is closed. Similar slots 8 are formed in the side walls of the element 6. The element 6 is provided with a pair of laterally extending apertured ears 9 for the passage therethrough of holdfast devices such as 10, by means of which the element 6 may be secured to any suitable support, such as a ceiling indicated at 11. The end walls of the element 6 are provided with openings 12 for the passage therethrough of the conductors 3 and 4.

End portions 13 and 14 of the conductors 3 and 4 respectively are stripped of insulation and bent into the form of hooks in interen gaging relation and disposed within the element 6. The end portions 13 and 14: are provided with a coating 15 of any suitable substance having a readily fusible characteristic in order that the same may quickly melt when subjected to heat. The portions 13 and 14; are normally maintained out of contact with each other by means of the coating 15 whereby the circuit in the fire alarm system or the like, with which the switch is associated, is normally maintained lhe' conductors 3 and 4 preferably are of flexible, non-resilient construction and are normally maintained taut in any suitable manner whereby the coating 15 on the end portion 13 is firmly held against the coating 15 on the end portion 14. One of the conductors, in the present instance the conductor 4, is provided on the insulated portion thereof disposed within the element 6 with a weight 16 which operates when the fusible substance 15 is melted to compensate for the space left between the end portions 13 and 14 by taking up the slack in the conductor 4 and drawing the end portion 14: into positive engagement with the end portion 13 whereby a positive contact is set up between the end portions. Owing to the operation of the weight 16, portions of the conductors per so may be utilized as contact points, and there is no possibility of a loose or ineffective connection between the end portions 13 and 14 after the fusible substance 15 has been melted therefrom.

It is thought that the many advantages of a thermo-electric switch in accordance with this invention will be readily apparent, and although the preferred embodiment of the invention is as illustrated and described, it is to be understood that changes in the details of construction may be resorted to, so long as such changes fall within the scope of the invention as defined in the appended claims.

What I claim is:

1. In a thermoelectric switch, a combined support and protector element, a pair of flexible, non-resilient conductors extending into said element and having end portions thereof coated with a fusible substance, said end portions being bent into the form of interengaging hooks and held out of contact with each other by said fusible substance, and means connected with one of said conductors for drawing said end portions into positive contact upon the melting of said fusible substance.

2. In a thermoelectric switch, a combined support and protector element, a pair of taut, flexible, non-resilient conductors extending into said element and having end portions thereof coated with a fusible substance, said end portions being bent into the form of intel-engaging hooks and held out of contact with each other by said fusible substance, and a weight carried by one of said conductors for drawing said hooks into positive contact upon the melting of said fusible substance.

3. In a thermoelectric switch, a combined support and protector element of box like form, a hinged cover for said element provided with slots to provide for the passage of heat into the interior of the element when the cover therefor is closed, said element being provided with a pair of openings, a pair of flexible, non-resilient conductors extending through said openings and having end portions thereof within the element coated with a fusible substance, said end portions being interengaged and held out of contact with each other by said fusible substance, and means connected with one of said conductors for drawing said end portions into positive contact upon the melting of said fusible substance.

4, In a thermoelectric switch, a combined support and protector element of box like form, a hinged cover for the element provided with slots to provide for the passage of heat into the element when the cover therefor is closed, said element having a pair of openings, a pair of taut, flexible, non-resilient conductors extending through the openings and having end portions thereof within the element coated with a fusiblesubstance, said end portions being bent into interengaging hooks held out of contact with. each other by said fusible substance, and a weight carried by one of said conductors and disposed within said element for drawing said hooks into positive contact upon the melting of said fusible substance.

5. In a thermoelectric switch, a combined support and protector element of box-like form, a hinged cover for said element, said element and cover havingslots to provide for the passage of heat into the interior of the element, a pair of flexible, non-resilient conductors extending into the element and having end portions thereof coated with a fusible substance, said end portions being interengaged and held out of contact with each other by said fusible substance, and means connected with one of said conductors for drawing said end portions into positive contact upon the melting of said fusible substance.

In testimo-ny whereof, I aflix my signature hereto.

RENO DE FRANCESC HI. 

